Two-cycle engines are widely used in utility and recreational vehicles, such as motorcycles and outboard engines. Injection systems for mixing lubricating oil with fuel have simplified the fueling process. Such injection systems avoid the necessity of premixing fuel and oil.
One major innovation in lubricant delivery systems for outboard motors is the use of two lubricating oil tanks: a first, oil delivery tank mounted on the engine to provide immediate availability of oil during startup and operation; and a second, larger remote tank for replenishing the smaller, motor-mounted tank. Such systems are disclosed, for example, in U.S. Pat. No. 4,403,578. An improved lubrication delivery system is disclosed in U.S. Pat. No. 4,572,120. This patent discloses an automated system, in which the lubricating oil level in the motor-mounted delivery tank is sensed by a level sensing switch. When the oil level in the delivery tank falls to a predetermined point, a pump is actuated to move oil from the larger, remote-mounted storage tank to replenish the delivery tank.
Although such systems reduce the bother associated with supplying lubricating oil to two-cycle motors, it is nevertheless important to keep the operator informed of the status of the lubrication system. Lubrication failures, of course, can result in major engine damage.
For this reason, U.S. Pat. No. 4,572,120 includes a status light system. A green, "system on" light indicates that the lubrication oil system is operating and that there is a sufficient level of lubricant in the delivery tank and the remote storage tank. A second, yellow warning light indicates that the level of oil in the storage tank is low. This allows the operator to replenish the oil supply.
Even when the oil in the remote storage tank is depleted, a properly-operating system will still have oil in the engine-mounted delivery tank. Thus, when the yellow caution light comes on, if it is not possible to replenish the oil supply, the operator at least knows that sufficient oil remains in the delivery tank to protect the engine during operation.
When the oil in the delivery tank is depleted, engine damage is eminent. Accordingly, a red warning light has been provided to indicate that the oil level in the delivery tank has fallen to a predetermined point.
The prior art system in U.S. Pat. No. 4,572,120 also provides an optional buzzer, together with an optional RPM limiter, to alert the operator to the low oil level in the delivery tank, and to conserve oil if it is necessary to operate the engine after the warning light is actuated.
The oil level indicator lights are an important part of the two-tank oil delivery system now in common use with two-cycle marine engines. There is a need to provide a system that includes such warning lights that is less expensive to construct, that provides a minimum parts count circuit, and that is more reliable in operation. These needs are addressed by the present invention.